ritual, offer prayers, celebrate, deify, enshrine, worship
祭 centers on formal acts of reverence: performing rituals, offering prayers, celebrating sacred occasions, and honoring or enshrining deities.
祭 combines 示 (altar, spirit) with an upper component that originally depicted a hand holding meat, suggesting an offering at an altar. The modern form retains the altar at the bottom while the upper part is stylized.
The bottom 示 is an altar. The top looks like a hand placing meat on it. Picture a ritual offering at a shrine: 祭 is a ceremony of worship and celebration.
For サイ, imagine a solemn ritual where everyone sighs in reverence: sigh -> サイ, as the offering is placed on the altar.
festival; feast; matsuri
priest; minister; pastor
festival
to deify; to enshrine
grand festival
altar
event held the night before another event; eve (of a festival) (e.g. Christmas Eve)
ritual; religious service; festival
Hinamatsuri (March 3); Hina Matsuri; Girls' Festival; Dolls' Festival
priest
national holiday
enshrined deity
important ceremonial occasions in family relationships
festivals; feasts
national holiday; festival day
autumn festival; fall festival; autumn matsuri
festival merrymaking; revelry
killing an enemy soldier before the start of a battle to raise spirits; blood offering
Gion Festival (in Kyoto during the month of July, with high point on the 17th)
funerals and ceremonial occasions